An endoscope of an endoscope system includes a channel of which a distal end forms a distal opening at a distal end of an insertion portion, of which a proximal end forms a proximal opening at an operating portion, and used for at least suction, and a suction duct of which a distal end forms a suction...http://www.google.co.uk/patents/US7775973?utm_source=gb-gplus-sharePatent US7775973 - Endoscope system
